how to in place update document : move element from one array to another ?

[Prashant Bhate]

With following document

Diagrams

{

name:'fig1',

pointsFrom:[point1,point2],

pointsTo:[],

moveCount:0

}

How to update above document and move point1 from pointsFrom to pointsTo array using collections.update api, without actually fetching complete object ?

update(

{name:'fig1'}, //criteria

{

 $inc:{moveCount:1}, 

 $pull: {pointsFrom:point1} ,

 $push:{pointsTo:point1}

},//Modifier

false,//upsert false

true //update multiple documents

)

[Louisa Berger]

Currently, you cannot use the fields of your document when updating a different field in your document. There's a good example for how to do work arounds for this general problem here : http://stackoverflow.com/questions/3788256/mongodb-updating-documents-using-data-from-the-same-document/3792958#3792958